Carbon dots as versatile photosensitizers for solar-driven catalysis with redox enzymes

Hutton, Georgina A. M., Reuillard, Bertrand, Martindale, Benjamin C. M., Caputo, Christine A., Lockwood, Colin W. J., Butt, Julea N. and Reisner, Erwin (2016) Carbon dots as versatile photosensitizers for solar-driven catalysis with redox enzymes. Journal of the American Chemical Society, 138 (51). 16722–16730. ISSN 0002-7863

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Light-driven enzymatic catalysis is enabled by the productive coupling of an enzyme to a photosensitizer. Photosensitizers used in such hybrid systems are typically costly, toxic and/or fragile, with limited chemical versatility. Carbon dots (CDs) are low-cost nano-sized light-harvesters that are attractive photosensitizers for biological systems as they are water-soluble, photostable, non-toxic and their surface chemistry can be easily modified. We demonstrate here that CDs act as excellent photosensitizers in two semi-biological photosynthetic systems utilizing either a fumarate reductase (FccA) for the solar-driven hydrogenation of fumarate to succinate, or a hydrogenase (H2ase) for reduction of protons to H2. The tunable surface chemistry of the CDs was exploited to synthesize positively charged ammonium-terminated CDs (CD-NHMe2+), which were capable of transferring photo-excited electrons directly to the negatively charged enzymes with high efficiency over 24 h. Enzyme-based turnover numbers of 6000 mol succinate (mol FccA)−1 and 43 000 mol H2 (mol H2ase)−1 were reached after 24 h. Negatively charged carboxylate-terminated CDs (CD-CO2–) displayed little or no activity and the electrostatic interactions at the CD–enzyme interface were determined to be essential to the high photocatalytic activity observed with CD-NHMe2+. The modular surface chemistry of CDs together with their photo-stability and aqueous solubility make CDs versatile photosensitizers for redox enzymes with tremendous scope for their utilization in photobiocatalysis.

Item Type: Article
Additional Information: ACS AuthorChoice - This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
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Depositing User: Pure Connector
Date Deposited: 01 Dec 2016 00:03
Last Modified: 21 Apr 2022 00:15
DOI: 10.1021/jacs.6b10146

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